Meroterpenes are encountered in microorganisms, plants and marine invertebrates and often exhibit substantial toxicity. Some terpenoid compounds, some of which display structural analogy to resveratrol. Bakuchiol is a meroterpene and a resveratrol structural analogue, with great potential for skin-beneficial activities. It is a structural analogue of resveratrol with retinol-like, skin-beneficial functionality, as revealed by comparative gene expression analysis [Chaudhuri R. K., et al., “Bakuchiol: A Retinol-Like Functional Compound Revealed by Gene Expression Profiling and Clinically Proven to Have Anti-Aging Effects,” Int. J. Cosmet. Sci. 2014; 36(3):221-230. doi: 10.1111/ics.12117; Chaudhuri, R. K., “Skin Appearance Through Gene Manipulation,” U.S. Pat. No. 8,859,021], as well as by its ability to induce same intracellular pathways, such as pro-differentiation, regenerative and pigmentation-inhibitory responses (Sato K, et al., “Depigmenting Mechanisms of all-trans retinoic acid and retinol on B16 melanoma cells,” Biosci. Biotechnol. Biochem., October 2008, 72(10):2589-2597; Ohno, O., et al., “Inhibitory Effects of Bakuchiol, Bavachin, and Isobavachalcone Isolated from Piper Longum on Melanin Production in B16 Mouse Melanoma Cells,” Biosci. Biotechnol. Biochem., 2010, 74(7):1504-1506; Chaudhuri, R K. “Compositions and Methods for Improving Skin Appearance,” U.S. Pat. No. 8,496,917; Li, W. D., “Osteoblasts Proliferation and Differentiation Stimulating Activities of the Main Components of Fructus Psoraleae corylifoliae,” J. Phytomedicine, 2014; 21(4):400-405, doi: 10.1016/j.phymed.2013.09.015). Unlike topical retinoids however, bakuchiol possesses direct antimicrobial, antiviral and antifungal activity (Shalita, A. “The Integral Role of Topical and Oral Retinoids in the Early Treatment of Acne,” J. Eur. Acad. Dermatol. Venereol., 2001, 15 Suppl. 3:43-49; Katsura, H. et al., “In vitro Antimicrobial Activities of Bakuchiol Against Oral Microorganisms,” Antimicrob. Agents Chemother., 2001, 45(11):3009-3013; Hsu, P. J., et al., “Bakuchiol, an Antibacterial Component of Psoralidium tenuiflorum,” Nat. Prod. Res., 2009, 23(8):781-788, doi: 10.1080/14786410902840158; Madrid, A., et al., “Antifungal Study of the Resinous Exudate and of Meroterpenoids Isolated from Psoralea glandulosa (Fabaceae),” J. Ethnopharmacol., 2012; 144(3):809-811, doi: 10.1016/j.jep.2012.10.027), including against Propionibacterium acnes (Chaudhuri, R. K., et al., “Bakuchiol in the Management of Acne-Affected Skin,” Cosmetics & Toiletries Magazine,” 2011, 126(7):502-510); as well as direct anti-oxidant effects (Haraguchi, H., et al., “Antioxidative Components of Psoralea corylifolia (Leguminosae),” Phytother. Res., 2002, 16(6):539-544; Adhikari, S., et al., “Antioxidant Activity of Bakuchiol: Experimental Evidences and Theoretical Treatments on the Possible Involvement of the Terpenoid Chain,” Chem. Res. Toxicol., 2003, 16(9):1062-1069; Conte da Froth, M. L. Jr., et al., “All-Trans Retinoic Acid Induces Free Radical Generation and Modulate Antioxidant Enzyme Activities in Rat Sertoli Cells,” Mol. Cell Biochem., 2006, 285(1-2):173-179). Another advantage of bakuchiol over retinoids is decreased potential for side effects, possibly linked to the lack of interference with retinoic acid receptors (Chaudhuri R. K., et al., “Bakuchiol: A Retinol-Like Functional Compound Revealed by Gene Expression Profiling and Clinically Proven to Have Anti-Aging Effects,” Int. J. Cosmet. Sci. 2014; 36(3):221-230. doi: 10.1111/ics.12117).
Nevertheless, the use of bakuchiol in dermatology and cosmetics may be limited by its brown color, relatively high cytotoxicity (Iwamura, J., et al., “Cytotoxicity of Corylifoliae fructus. II. Cytotoxicity of Bakuchiol and the Analogues,” Yakugaku Zasshi, 1989, 109(12):962-965). Bakuchiol is also known to have a high production cost and instability upon long-term storage (Hsu, P. J., et al., “Bakuchiol, an Antibacterial Component of Psoralidium tenuiflorum,” Nat. Prod. Res., 2009, 23(8):781-788, doi: 10.1080/14786410902840158) or illumination with UVB light.